Why is my lower pulley wobbling?

Discussion in ''Da Nailhead' started by 1966buickgs, Apr 13, 2018.

  1. 1966buickgs

    1966buickgs 1966buickgs

    I have already pulled the harmonic balancer to have it tested again cause the engine was rebuilt last year. Now the machinist is asking me to measure the run out on the crank. How do I do that properly? I'm hoping its just the harmonic balancer gone bad. When the balancer was installed it was torqued to 220 lbs. No oil is leaking from the timing chain cover an the alternator an power steering belts were tight but still a definite wobble on the crank pulley. What else could it be?
    Devin likes this.
  2. Briz

    Briz Platinum Level Contributor

    Is the pulley bolted on flush and tight?
  3. woody1640

    woody1640 Well-Known Member

    And both mating surfaces are nice and clean, so parts fit tight together correctly?

    A member of our 61-63 group just did a flywheel swap and did not clean the surfaces properly, and his starter wouldn't reach lol. After pulling it back apart and cleaning both surfaces good everything fit fine and the starter spun the flywheel over.

  4. 1966buickgs

    1966buickgs 1966buickgs

    Yes everything was cleaned and fit together tight an torqued to spec,flywheel an harmonic balancer.
  5. Mart

    Mart '71 350 GS, almost stock

    Bent pulley. If it bolts to inner balancer hub like most & not the outer ring, balancer shouldn't be the issue. Maybe somehow got bent?
  6. 1966buickgs

    1966buickgs 1966buickgs

    The pulley is straight not bent what so ever. Put on oem pulleys for a 401 with a/c that I bought an replaced the originals cause the lower pulley was bent up when i got the car. The motor was not locked up but did not run,then I had it completely rebuilt last year.
  7. 8ad-f85

    8ad-f85 Well-Known Member

    Mount your indicator to run along each surface and turn the engine by hand.
    You'll find all kinds of places you can check the snout and dampener.
    The worst is that the crank or a main cap is cracked and on it's way to telling you more.
  8. Houmark

    Houmark Well-Known Member

    My lower pulley does the same thing.. When I noticed, I pulled it, cleaned all surfaces and painted it.. When I'd put it on again, I was very careful with having it straight on and snugging the bolts in the right order.. Still wobbles a little, but it has done it 5 years no problems.. My 401" has never been opened, so everything is stock

    STAGE III Lost Experimental Block

    Wonder since the motor was stuck if someone previously put a massive breaker bar on it and did internal damage? Sounds like everything is fine on the outside so inside is all that's left?
  10. Mart

    Mart '71 350 GS, almost stock

    How bad is it? Enough to throw belts? If it wobbles, tweek it some so it doesn't.
  11. 1966buickgs

    1966buickgs 1966buickgs

    The motor has been rebuilt last year an there are no knocks,oil pressure is good,an the motor runs so broken crank or main cap not it I would hope. What order are the bolts supposed to be snugged when putting the pulley back on? The motor wasn't stuck when I got it but probably been before the way the lower original pulley was bent,maybe from breaking it loose but I had the motor rebuilt. An yes it wobbles enough to where it has slung off two power steering belts an broke a alternator belt so yes it wobbles to much.
  12. Aussie V8

    Aussie V8 Well-Known Member

    That sounds serious :eek:
    From what I remember when playing around with my pulley, it seems to be made up of two pieces ?? Maybe it is separating ?
    I would take it off right now before any serious damage is done - and replace it.

    JESUPERCAT No Slow Boat

    Does the balancer wobble.
    When a balancer gets loose or is damaged it can narrow the crank snout.
    I had a crank that was narrowed to the point you could see it with the balancer off.
    We machined the crank and bushed the end.
    8ad-f85 likes this.
  14. gsgtx

    gsgtx Silver Level contributor

    i would take the pulley off and run it to see if the damper is the problem.

    JESUPERCAT No Slow Boat

    Check the key for damage also crank and balancer.
  16. 1966buickgs

    1966buickgs 1966buickgs

    Took the balancer back to the builder who tested and it did have a wobble. Tried to test the crank for run out with s clamp dial indicator with a read out of 1/100"(outside), 10/90"(inside). I don't know how to accurately use this indicator properly on the crank snout but visibly it looks like when I turn it over it has lobe or wobble to it also. I don't know how it happened. The key way still looks good on the crank snout an no visible damage!!!Damn!!! What's next!!!
  17. 8ad-f85

    8ad-f85 Well-Known Member

    It is possible for an indicator to move a bit depending on how it sits against the shaft or is rigged, when the shaft begins to rotate. You'll have to rule that out. Tough to describe, it's one of those "have to be there" things.

    Again, not trying to scare you...the one I eventually saw with a broken main cap and bent crank had only a 5 psi less running oil pressure and then the even rhythmic drop as it worsened. It was also fairly fresh and you'd never see that at that stage. (I was a teenager and brought it to several places. None of which could tell me what was happening. It worsened the more I beat it, until the cause was obvious)

    All that aside, the crank shaft needs to be removed and resolved if it is indeed bent.
    Being "rebuilt" rules out nothing. Many of us make a living by being more meticulous than the last guy.
  18. 1966buickgs

    1966buickgs 1966buickgs

    Thank you all for the information! I made a video of testing the run out on the crank with the dial indicator applied to the side of the snout of the crank. Then I took it to the machine shop who built my engine. The builder thinks that the crank is still good. Im waiting on the balancer rebuild now,Im hoping the rebuilt balancer will solve this.
  19. Mart

    Mart '71 350 GS, almost stock

    Your pulley doesn't bolt to the external balance ring of the balancer. Rebuilding balancer should not have anything to do with it wobbling.?

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